One of the major concerns of integrated utilization of Web-based rich multimedia systems and mobile computing technologies is a low security level of communications and transfer of confidential rich multimedia files over mobile networks. Virtual Private Network technology proved to be one of the most reliable technologies to provide data protection, confidentiality, integrity, data origin authentication, replay protection and access control in mobile computing. This paper presents the outcomes of research, design and development project on creation of secure communications in Web-based rich multimedia systems and performance analysis of encryption algorithms in cipher-block chaining mode in IPsec-based mobile virtual private networks.